1. Field of the Invention
The present invention relates to a waterproof/dustproof structure for an apparatus having a mechanism composed of a stationary member and a movable member. The waterproof/dustproof structure is applicable to an apparatus such as a machine tool having a movable member whose movement is required to be precise.
2. Description of Related Art
In a mechanism having a movable member whose movement is required to be precise, for example the movable member of a machine tool, in order not to impede the movement of the movable member it is desirable not to have the stationary member and the movable member in fixed contact with each other. However, not having the stationary member and the movable member in fixed contact with each other means that a gap exists between the two members, which in turn necessitates preventing fluid and particles from entering the interior of the machine tool or other apparatus through that gap.
As a waterproof/dustproof structure effective in preventing the entry of fluids and particles into the interior of the apparatus through this sort of gap between the stationary member and the movable member, forming a labyrinth of minute vacant spaces in the gap formed between a fixed member and a movable member that are not in fixed contact with each other is known conventionally.
FIG. 1 is a diagram showing a cross-sectional view of a labyrinth according to the conventional art. In FIG. 1, reference numerals 1 and 2 designate the stationary member and the movable member, respectively, with a gap 3 formed between the two members. Typically, the direction of movement of the movable member 2 with respect to the stationary member 1 is either (1) horizontally, perpendicular to the surface of the paper, or (2) vertically, within the plane of the drawing. In general, however, the direction of movement is such as to hold the gap 3 constant, and depending on the mechanism to which it is applied, the direction of movement can also be a combination of (1) and (2), (that is, a slanting vertical direction).
In such a labyrinth, the gap 3 between the stationary member 1 and the movable member 2 is slight, and further, since contact between the members is not permitted, the respective members (or parts that comprise the members) are required to be formed with a high degree of precision, and moreover, they must also be assembled with great precision. These requirements are disadvantageous because they increase the cost of the members and parts and because they increase the number of assembly steps. In addition, although the labyrinth forms the boundary between the interior and the exterior of the apparatus (for example, a machine tool) having a movable mechanism, despite its narrowness, it still constitutes a path by which foreign matter crosses that boundary from the outside of the apparatus (the surrounding environment) to the inside of the apparatus.
As a result, as shown in the drawing, with long use comes the possibility of particles of dust or the like and water particle mist and so forth getting inside the apparatus and contaminating the interior of the apparatus. In addition, particles and mist components sometimes adhere to the inner walls of the narrow gap 3 and can obstruct the smooth movement of the movable member 2.
As a common technique for preventing the entry of foreign matter through the gap between the two members there is a method involving the use of an air curtain-like air flow (see, for example, JP 2004-286109A). However, a problem with this method is that the mechanism that forms the air flow is complicated.